From Wikipedia

The Plot To Overthrow FDR

The Business Plot (also the Plot Against FDR and the White House Putsch) was a supposed political conspiracy in 1933. Retired Marine Corps Major General Smedley Butler claimed that wealthy businessmen were plotting to create a fascist veterans' organization and use it in a coup d’état to overthrow United States President Franklin D. Roosevelt, with Butler as leader of that organization. In 1934 Butler testified to the McCormack-Dickstein Congressional committee on these claims. In the opinion of the committee, these allegations were credible. One of the purported plotters, Gerald MacGuire, vehemently denied any such plot. In their report, the Congressional committee stated that it was able to confirm Butler's statements other than the proposal from MacGuire which it considered more or less confirmed by MacGuire's European reports. No one was prosecuted.

While historians have questioned whether or not a coup was actually close to execution, most agree that some sort of "wild scheme" was contemplated and discussed. Contemporaneous media initially dismissed the plot, with a New York Times editorial characterizing it as a "gigantic hoax". When the committee's final report was released, the Times said the committee "purported to report that a two-month investigation had convinced it that General Butler's story of a Fascist march on Washington was alarmingly true" and "It also alleged that definite proof had been found that the much publicized Fascist march on Washington, which was to have been led by Major. Gen. Smedley D. Butler, retired, according to testimony at a hearing, was actually contemplated".